LVV-hemorphin-7 (LVV-H7) plays a role in antinociception in a rat model of alcohol-induced pain disorders

Nalbuphine-6-glucuronide is a potent analgesic with superior safety profiles by altering binding affinity and selectivity for mu-/kappa-opioid receptors

Although nalbuphine, a semi-synthetic analgesic compound, is less potent than morphine in terms of alleviating severe pain, our recent findings have revealed that nalbuphine-6-glucuronide (N6G), one of the glucuronide metabolites of nalbuphine, promotes a significantly more robust analgesic effect than its parent drug. Nevertheless, despite these promising observations, the precise mechanisms underlying the analgesic effects of nalbuphine glucuronides have yet to be determined. In this study, we aim to elucidate the mechanisms associated with the analgesic effects of nalbuphine glucuronides. Pharmacokinetic and pharmacodynamic studies were conducted to investigate the relationship between the central and peripheral compartments of nalbuphine and its derivatives. The analgesic responses of these compounds were evaluated based on multiple behavioral tests involving thermal and mechanical stimuli. Radioligand binding assays were also performed to determine the binding affinity and selectivity of these compounds for different opioid receptors. The results of these tests consistently confirmed that the heightened analgesic effects of N6G are mediated through its enhanced binding affinity for both mu- and kappa-opioid receptors, even comparable to those of morphine. Notably, N6G exhibited fewer side effects and did not induce sudden death, thereby highlighting its superior safety profile. Additionally, pharmacokinetic studies indicated that N6G could cross the blood-brain barrier when administered peripherally, offering pain relief. Overall, N6G provides great analgesic efficacy and enhanced safety. These findings highlight the potential value of nalbuphine glucuronides, particularly N6G, as promising candidates for the development of novel analgesic drugs.

New N- and C-modified RGD-hemorphins as potential biomedical application on Ti-surface materials: synthesis, characterization and antinociceptive activity

This manuscript presented the synthesis and characterization of two new N- and C-modified analogues of VV-hemorphin-7 containing RGD (Arg-Gly-Asp) residues as potential nociceptive agents and bioactive materials. It has been shown that the addition of one or two RGD sequences to natural VV-hemorphin-7 increases its effect on acute nociception, but the reduction of the inflammatory phase depends on the concentration of the peptide. The structure-property relationship of the new peptide derivatives was highlighted by electrochemical and FT-IR methods of analysis. Because of the proven bone-structural bonds of hydroxyapatite, the simultaneous deposition of peptide/hydroxyapatite on the surface of a titanium surface was investigated. The deposition was performed in a medium of gelatin solution containing dissolved amounts of peptide and hydroxyapatite using ultrasound. SEM-EDS analyzes confirmed the presence of a layer of the studied system.

Interactions Among Non-Coding RNAs and mRNAs in the Trigeminal Ganglion Associated with Neuropathic Pain

Background

Recent studies have demonstrated the contribution of non-coding RNAs (ncRNAs) to neuropathic pain. However, the expression profile of ncRNAs in the trigeminal ganglion (TG) and their functional mechanism underlying trigeminal neuropathic pain are still unclear.

Methods

In the present study, the trigeminal neuropathic pain model induced by chronic constriction injury of the infraorbital nerve (CCI-ION) was used to study the expression profile and potential regulatory mechanism of miRNAs, lncRNAs, circRNAs, and mRNAs in the TG by RNA-sequencing (RNA-seq) and bioinformatics analysis. CCI-ION mice suffered from mechanical allodynia from 3 days to 28 days after surgery.

Results

The RNA-seq results discovered 67 miRNAs, 216 lncRNAs, 14 circRNAs, 595 mRNAs, and 421 genes were differentially expressed (DE) in the TG of CCI-ION mice 7 days after surgery. And 39 DEGs were known pain genes. Besides, 5 and 35 pain-related DE mRNAs could be targeted by 6 DE miRNAs and 107 DE lncRNAs, respectively. And 23 pain-related DEGs had protein–protein interactions (PPI) with each other. GO analysis indicated membrane-related cell components and binding-related molecular functions were significantly enriched. KEGG analysis showed that nociception-related signaling pathways were significantly enriched for DE ncRNAs and DEGs. Finally, the competing endogenous RNA (ceRNA) regulatory network of DE lncRNA/DE circRNA-DE miRNA-DE mRNA existed in the TG of mice with trigeminal neuropathic pain.

Conclusion

Our findings demonstrate ncRNAs are involved in the development of trigeminal neuropathic pain, possibly through the ceRNA mechanism, which brings a new bright into the study of trigeminal neuropathic pain and the development of novel treatments targeting ncRNAs.

Risk Factors for Poor Pain Control in Zoster-Associated Pain: A Retrospective Study

INTRODUCTION

The objective was to investigate the risk factors for poor pain control in patients with herpes zoster (HZ)-associated neuropathic pain treated with drugs combined with nerve block therapy. Neuropathic pain commonly follows HZ. Nerve block therapy is the most commonly used clinical treatment for such pain, combining anti-inflammation and analgesia to prevent peripheral sensitization of nerve.

METHODS

Using clinical practice data from a cohort study at our research center, we established a multivariate logistic regression model to investigate potential risk factors for poor control of zoster-associated pain (ZAP) treated with drugs plus nerve block therapy, including demographic characteristics, complications, laboratory tests, and characteristics of HZ attacks.

RESULTS

Of the 429 patients with ZAP who received drugs plus nerve block therapy, 95 (22.14%) had poor pain control after treatment. The risk of poor pain control was closely related to presence of cancer (odds ratio (OR) 4.173, 95% confidence interval (CI) 1.342-12.970), numerical rating scale score on admission (OR 1.929, 95% CI 1.528-2.434), and red blood cell count (OR 0.560, 95% CI 0.328-0.954). Area under the receiver operator characteristic curve was 0.730. Goodness of fit (Hosmer-Lemeshow) was 0.874.

CONCLUSIONS

The risk of poor pain control in patients with ZAP increased as a result of certain patient characteristics and complications, especially severe pain before treatment and cancer.

Patients with alcohol use disorder increase pain and analgesics use: A nationwide population-based cohort study

BACKGROUND

Alcohol has dual effects on many systems, including the pain system. We will test whether and how chronic alcohol consumption enhances pain sensation to develop pain disorder.

METHODS

We conducted a retrospective matched cohort study using data from the National Health Insurance Research Database (NHIRD) in Taiwan, in patients with and without alcohol use disorder (AUD). This study enrolled 19,174 individuals with AUD as study cohort and 19,174 propensity score-matched individuals without AUD as comparison cohort. The outcome was the incidence of pain disorders and the need for analgesics. The hazard ratios of pain disorders and the need for analgesics were evaluated using Cox proportional hazard regression analysis after adjusting for age, sex, index year, comorbidities, urbanization, areas of residence, and insurance premium.

RESULTS

The 14 years of follow-up showed that AUD patients had a higher adjusted hazard ratio (aHR) for developing pain disorders than in non-AUD controls [aHR= 1.290, 95% confidence interval (CI): 1.045-1.591]. Besides, AUD patients had a higher risk of analgesic use (aHR = 1.081, 95% CI: 1.064-1.312), including opioids and non-opioid analgesics. Most importantly, AUD patients required more days of analgesic use, increased dose of analgesics, and higher costs of analgesics. Moreover, AUD patients had more anemia (aHR=2.772, 95% CI: 2.581-2.872), which could be a mediating factor.

CONCLUSIONS

AUD patients had higher risks of developing pain disorders and subsequently increased analgesic demand. These results suggest that AUD worsened pain, and pain syndrome is correlated with the duration of chronic alcohol exposure.

Hemorphins-From Discovery to Functions and Pharmacology

During the last three decades, a variety of different studies on bioactive peptides that are opioid receptor ligands, have been carried out, with regard to their isolation and identification, as well as their molecular functions in living organisms. Thus, in this review, we would like to summarize the present state-of-the art concerning hemorphins, methodological aspects of their identification, and their potential role as therapeutic agents. We have collected and discussed articles describing hemorphins, from their discovery up until now, thus presenting a very wide spectrum of their characteristic and applications. One of the major assets of the present paper is a combination of analytical and pharmacological aspects of peptides described by a team who participated in the initial research on hemorphins. This review is, in part, focused on the analysis of endogenous opioid peptides in biological samples using advanced techniques, description of the identification of synthetic/endogenous hemorphins, their involvement in pharmacology, learning, pain and other function. Finally, the part regarding hemorphin analogues and their synthesis, has been added.

Hemorphins Targeting G Protein-Coupled Receptors

Hemorphins are short peptides produced by the proteolysis of the beta subunit of hemoglobin. These peptides have diverse physiological effects especially in the nervous and the renin-angiotensin systems. Such effects occur through the modulation of a diverse range of proteins including enzymes and receptors. In this review, we focus on pharmacological and functional targeting of G protein-coupled receptors (GPCRs) by hemorphins and their implication in physiology and pathophysiology. Among GPCRs, the opioid receptors constitute the first set of targets of hemorphins with implication in analgesia. Subsequently, several other GPCRs have been reported to be directly or indirectly involved in hemorphins’ action. This includes the receptors for angiotensin II, oxytocin, bombesin, and bradykinin, as well as the human MAS-related G protein-coupled receptor X1. Interestingly, both orthosteric activation and allosteric modulation of GPCRs by hemorphins have been reported. This review links hemorphins with GPCR pharmacology and signaling, supporting the implication of GPCRs in hemorphins’ effects. Thus, this aids a better understanding of the molecular basis of the action of hemorphins and further demonstrates that hemorphin-GPCR axis constitutes a valid target for therapeutic intervention in different systems.